Electric calculating machine



Feb. l2, 1946-.

H. P. LUHN ELECTRIC CALCULATING MACHINE Filed latch 30, 1943 l 14 Sheets-Sheetl 1 FIGQ. a.

SYM

l2, 1946. H, P, LUHN 2,394,924

ELECTRIC CALCULATING MACHINE Filed' March 30, 1943 14 Sheets-Sheet 2 J," l/EETQE TTQRNEY Feb. l2, 1946. H. P. LuHN ELECTRIC CALCULATING MACHINE 14 sheets-sheet s Filed March 30, 1943 F IG. Ic.

ATTORNEY Feb. l2, 1946. H. P. I UHN vELECTRIC CLCULATING MACHINE Filed March 30, 1943 14 Sheets-Sheet 4 FIG. Id.

fmII-If I -I--f--n ATTQRNEY 14 sheets-sheet 5 H. P. LUHN ELECTRIC CALCULATING MACHINE Filed March 3D, 1943' T1 r.. W U m 4m, 1| z llilllr Y R 1| v www@ l H M 62| llllllll l l||| wv /L w -i IIII Il W72l lllllllllllll Il Feb. l2, 1946.

SEIIIIIIIIIlRI! Feb. 12, 1946. H. P. LUHN ELECTRIC CALCULATING MACHINE 14 Sheets-Sheet 6 Filed March 30, 1943 FIG. 1F.

'INVENTOR m B M 1 ATTO R N EY Feb.12,1946. H. F. LUHN 2,394,924

I ELECTRIC CALCULATING MACHINE Filed March 50, 1943 14 Sheets-Sheet 7 ATTORNEY Feb. l2, 1946. H. P. L UHN 2,394,924

ELECTRI C CALCULATI NG MACHINE Filed March 30, 1943 14 Sheets-Sheet 8 ATTORNEY Feb. 12, 1946.

ELECTRIC CALCULATING MACHINE Filed March 30, 1943 14 Sheets-Sheet 9 Flan.

Ril/a ATTORNEY Feb. 12, 1946. H. P. LUHN 2,394,924

ELECTRIC CALCULATING MACHINE INVENTO Feb. l2, 1946. H. P. LUHN 2,394,924

ELECTRIC CALCULATING MACHINE Filed March 30, 1943 14 Sheets-Sheet 1l #lV/I5 8 6 4 2 0 n b A l l i c2 4 AZ4a Y 4 y Z n f4.2@

c O FIG Ik o a a a /6 M2 @44 1 n.4@

,98.4 R@ ggd I .a ./L H00 .1,1/6

' ATTORNEY Feb. l, 1946. H P, LUHN 2,394,924

ELECTRI C CALCULAT ING MACHNE Filed March C50, 1943 14 Sheets-Sheet l2 nvl gyTOR BY ATTORN EY Feb. l2, 1946. H, P, LUHN 2,394,924

ELECTRIC CALCULATING MACHINE i Filed March 30, 1943 14 Sheets-Sheet 13 40 ,v0/mens 39 `llrr'ToRNEY Patented Feb. 12, 1946 2.394.924 ELECTRIC CALCULATING MACHINE HansP.Lnhn.Armonk,N.Y.,aaaignoi-to national Business Machines Corpo York, N. Y.,

ration, New

a corporation of New York Alplicatlon March 30, 1948, Serial No. 1,075 15 Claims. (Cl. 23H1) This invention relates .to calculating machines and more particularly to machines for performing multiplying and dividing operations.

The principal object of the invention is to prolvide an improved form of electrical multiplying machine in which multiplying is effected instantaneously upon the setting of factors on the key- A further object of the invention is to provide a common mechanism which functions in one manner to perform multiplication and in another manner to perform division.

A specific object of the invention is to provide improvedl relay adding mechanism for summing a plurality of subproducts to form a complete product.

A more specific object of the invention is to provide improved tens carry mechanismv for a relay adding mechanism whereby tens carry operations may occur simultaneously with the adding operations in a relay accumulator.

A further specific object is to provide improved comparing mechanism i'or comparing a dividend amount with a succession of trial products in the performance of dividing operations.

A still further object of the invention is to provide improved mechanism for automatically obtaining the square root of a number.`

l Other objects oi' the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle. 1

In the drawings:

Figa, la, 1b, 1c, 1d, 1e, lf, 1g. 1h, 1i, 1j, ik, 1m

I and ln, taken together and arranged in the order shown in Fig. 4. constitute a wiring diagram and schematic arrangement of the complete machine. l'ig. 2 is a diagram showing the general method o! multiplying employed.

Fig. 3 is a similar diagram outlining the method emnlvnd in a more detailed manner.

Hg. 4 is a diagram showing the manner in which-the ilgu'res of the circuit diagram are to be arranged The general theory of operation will first be explained with particular reference to Figs. 2 Aand 3. A machine is provided with a. keyboard which, for multiplying operations, is operated to set multiplicand and multiplier amounts and through cirious subproducts 35, 40, 63, 72 obtained when 87 is multiplied by 95. I'he selected relays are denominationally arranged so that the subproducts are separately added with tens carry between orders. Thus, in Fig. 2 the 3 of the 35 is carried i into the second order from which l is carried to the third order from which in turn 8 is carried to the fourth order to obtain the product 8,265 as a result of adding the several subproducts. Fig. 2 represents the general procedure followed in multiplying. In Fig. 3 the procedure is set forthdn greater detail.

In handling the same problem of 87x95 in the present machine, the various digits are represented in accordance with the binary system of notation, which is the well known 4 position combinational code system. Thus, in Fig. 3 the two numbers to be multiplied are indicated by their `combinational values. Thus, 87 is represented by an 8 and the 7 by a 4, 2, 1 combination. Sets oi relays are provided for each denominational order, and these relays have values in accordance with the terms of the binary progression. Upon setting of the keys to represent factors to be multiplied.

2s valued relays are selectively energized in the sevcuits controlled by the keys relays are automatically selected and energized to represent the several subprcducts obtained as a result of the multiplication. For example, Fig. 2 represents the vareral orders as shown in Fig. 3. Thus, in the units column the multiplication of the units digit 7 of the multiplicand by the units digit 5 ofthe multiplier will energize relays valued at l, 2, 4. 4, 8, and i6, the sum of these being 35, and the selected values represent the multiplication of each binary term oi' the multiplier digit by each of the binary terms of the multiplicand digit as indicated. Bimilarly, in the tens column the multiplication oi' the 8 and 5 digits selects the 8 and 32 valued relays, and the multiplication of the 9 and 7 digits in the same order selects magnets whose aggregate value is 63. Selection oi' adding relays in the several orders also causes selection of carry relays generally designated by the preiix C, which as indicated in Fig. 3 add further values in higher orders. The manner in which the various operations outlined in Fig. 3 are carried out in the mechanism will now be explained with particular reference to the circuit diagram, and in explaining the operation the specific example o! Fig. 3 will be followed.

Referring to Figs. 1c and id. there are diagrammatically shown multiplier or divisor keys designated Il and multiplicand keys designated Il. Two orders are provided for multiplying two digits by two digits, which is the capacity of the arrangement shown. Each of the keys is arranged, when depressed, to be held by a spring- .pressed iatching bar designated I2, and depresthe4andicontactsll,andthe9keyilin the tens order will close the 8 and l contacts il. 'I'he multipilcand keys II are arrangedto close contacts I`4 arranged in the same manner as the contacts I2, so that for the example chosen the 7 key II in the units order will close the 4, 2 and i contacts I4 in line with the '1 key. andinthetensorder the8key II willclosethe contacts I4. l Referring to Fig. lb, current is supplied from a suitable source to positive line il and negative line Il, which lines-extend` through the several sections of the circuit diagram. As a preliminary to multiplying operations, a key I1 (Fig. le) is operated to shift a pair of contacts I8 from the position shown, and auch key will thereafter remain held depressed by one of the latching bars '|2.

Referring to Figs. la and lb, there is provided a set of relay magnets designated Il for each of the two orders. Each set has one magnet for each of the first four terms of the binary progression as indicated bythe numerals I, 2, 4, l, and each relay has a double winding with the two windings being opposite in direction. Depression of the multiplicand keys II will energize the relays I l in accordance with the binary equivalent of the multiplicand digits. Thus, for the imita digit 'Lof the multiplicand, the l, 2 and 4 relays I8 in the units order (Fig. l) will become energized, and for the tens multiplicand digit 8, the 8 magnet Isin the tens order of Fig. 1b will become energized. The circuits involved are emphasized in heavy lines on the circuit diagram and are traceable as follows:

In Fig. 1c from positive line Il. through the l, 2 and 4 contacts I4 of the 'I key II, the l, 2, 4 wires of a group designated, normally closed contacts Ria, the l, 2, 4 wires of a group designated 2i (Fig. la), the upper windings of the l, 2, 4 relays i8, common wire 22 (Figs. 1b, ld

and le) the lower contacts I8 to negative line I8.

Through concurrent circuits, the 8 magnet I8 of the tens order (Fig. 1b) is energized. This circuit is traceable from positive line I5 (Fig. ld) the 8 contacts I4 related to the 8 key, the 8 wire of the group designated of the tens order, normaliy closed relay contacts RIb, the 8 wire of the group 2I of the tens order (Fig. lb), the upper winding of the 8 relay I8 in the tens order to the common wire 22, and thence to negative line I8 as traced for the units order circuit.

Each of the relays I8 closes a set of eight contacts designated 28,' a single contact designated 24, and additional contacts designated 25. I'he related contacts for the l, 2 and 4 relays I8 in Fig. la and the 8 relay I8 in Fig. lb will accordingly be shifted. These contacts jointly with the contacts I2 closed by the multiplier keys I0 will now concurrently complete a plurality of circuits to energize relay magnets shown in Figs. la and ik for the unitsorderand in Figs. lh and lm for the tens order. Before tracing the circuits through the relay magnets, a brief explanation will be given of their function.

Referring to Figs. la and 1k, the relay magnets are designated by the letter R followed by two digits separated by a dot, `indicating that the relay is responsive to multiplication of the two digits indicated. Inspection of Figs. 1a and lk shows that the digits involved are-l, 2, 4 and 8. It will be noted that the combinations of any of the four digits 1,2,4and8with eachofthe same four digits gives sixteen possible combinations.- In Fig. lk, several of the relays have a common core, said core being provided for combinations which will not occur at the same time for' any problem.

Each of the relays, when energized, will shift the set of contacts at the right thereof which are identified by the same reference character as the relay suflixed by the letter a. These contacts are interconnected through what may be termed an adding circuit generally, which will become addusted in response to the energization of the relays in Figs. la and lk to complete a circuit representing the units digit of the sum of the products e represented by the relays. The sets of contacts are separated by horizontal dotted lines with the groups designated generally l, 2, 4, 8, 18, 82 and 84, these numbers indicating the several subproducts to be selectively added by the circuit chain.

Referring to Fig. 3, it will be noted that for the problem under consideration the binary terms i6, 8, 4, 4, 2 and l are to be added. Accordingly, the relays designated in parentheses in Fig. 3 are to be energized. `The circuits involved will now be traced.

For relay RIA; from negative line Il (Fig. lc), relay contacts Rta normally closed, wire 28, the 4 contacts Il ofthe 5 key Il, the 4 contacts of a group designated Rlla, the 4 wire of a group designated 21 (Figs. la and 1k), relay RIA, a wire in the 4 set generally designated 28 (Figs. la, lc, la), the related contacts 28 in line with the4 relay I8,topositive line Il.

For relay R42; from negative line I8 (Fig. lo), relay contacts Rla normally closed, wire 2t. the 4 contacts Il of the 5 key I0. the 4 contacts of a group designated Riila, the 4 wire of a group designated 21 (Figs. l0 and lk), relay R41, a wire in the 2 set which is generally designated 28 (Figs. la, lc, la), the related contacts 2l in line with the 2 relay Il, to positive line Il.

For relay RU; from negative line I8 (Fig. lc), relay contacts Rla normally closed, wire 28, the 4 contacts I! of the 5 key III, the 4 contacts of a group designated RIIIa,'the 4 wire of the group designated 21 (Figs. \lc, lo), relay R4.I, a wire in the l set which ii"generally designated 2l (Figs. lc, la). the related contacts 28 in line with the l relay I8, to hpositive line Il.

ForY relay RIJ;` from negative line Il (Fig. lc), relay contacts' Ria, wire 28, the l contacts I2 of the' key I8, contacts Rlb. the 1 contacts Rina, .the l wire of thegroup 21 (Fig. la), relay RIA, a wire of the 4 set designated 2l (Figs. lc. la), to another of the contacts 2l in line with the 4 magnet I l, to positive line Il.

For remy nu; from negative une n (rig. 1c).

relay contactaRla. wire 24, contacts Il of the 5 key I0, contacts Rib, the l contacts RlIIa, the l wire of the group 21'(Fig. la), relay RIJ, wire of the 2 set designated 28 (Figs. lc, la), to another of the contacts 2l in line with the 2 magnet I8, to positive line Il.

For relay RI.I; from negative line Il (Fig.

lc). relay contacts Ria, wire 2l. contacts I8 of the 5 key II, contacts Rtb, the l contacta Rliia, the l wire of the group 2l (Fig..1a), relay RIJ, wire of the l set designated 2l (Figs. lc, la), to

. 3. anotheroithe'contacts 28inlinewith the lmag- 1c, la), one of the contacts 28 of the 1 relay Ill W .I8. topositiveline I8. the units order. to positive lino Il.

These circuitsare emphasised in heavy lines Through the circuits Just traced the relays on the drawings to facilitate their tracing. and it listed in the tens columnof Fig. 3 are concur. noted that the relays indicated for the l rentlv energized along with the relays listed in unita order in Fig. 8 are now all energized. The the units column 'I'hrough the following circuits eirwits for energizing the relays in the tens orthe two relays listed in the hundreds column of l der will now also be traced, and these have also Fig. 3 will also be energized at the same time. 'been' emphasised inheavy lines on the circuit For relay 11.8.8: negative line I8 (Fig. 1c), conv l"` tacts R841, wire 28 (Fig. 1d) 8 contacts I8 of the 9 s ForrelayR8.8; negative line I8 (Fig. 1c). conkey in the tens order, 8 contacts RIIIa, the 8 tactg R86, Wire 28, 4 contacts I8 of the 5 key, wire; 21 (Figs. 1h, 1m), wire 81 (Fig. 1n), relay contacts RIM, the 4 wire 21 (Figs. -ln and 1k). 11.8.8, wire 88 (Fig. 1m), one o! the 8 wires 28 of wire 28 (Fig. 1m). relay 12.8.8.` a wire in the 8 the tens order (Figs. 1h, 1b, 1d), pair of conest oi the group of wires 28 for the tens order ls tacts 28 of the 8-relay I8 in the tens order to tligs. 1h, ld, 11:,` the related contacts 28 in line positive line Il.

with the 8 magn t I8 in the tens order to posi- For relay RIJ; negative line I8 (Fig. lc), contiva line Il. tacts Rla. wire 28 (Fig. 1d), the 1 contacts I8 of For the relay RM; negative line I8 (Fig. 1c). the 9 key in the tens order, the 1 contacts Rila. contacts 38a, the l contacts I8 inthe 5 key, 2o the 1 wire 21 (Figs. 1h and 1m), wire 88 (Fig. ,mots RID. the l contacts RIM, the 1 wire 21 1n), relay RIJ, wire 88 (Fig. 1m), one of the 8 ai nauwe-e sa bofilile 9 key in the tens the 118th, the

(Figs. lo, llc) .l wire 88 (Fig. 1m), relay RIJ, an-

omtacts 28 of the group in line with the 8 magne't`l8.topositive line I8. i

The foregoing circuits energize relay magnets `in accordance with the multiplication of the umts (digit oi' the multiplier andboth digits of the multiwould In the following the circuits vwill be v 'for energization of relays in accordance liththe' multiplication of the tens digit of the multiplier and the two multiplicand digits as indicated in Fig- 3- t For the relay 11.8.8; from negativeline I8 (Fig. le), contacts R80; wire 28 (Fig. 1d), the 8 contacts I8 0f the 9 key in the tens order, the 8 contacts RIIa, the 8 wire 2l (Figs. 1h, 11n), relay 88.8.wire 8l (Fig. lk). oneoi' the 4 wires 28 (Figs 1g, lc, la), contacts 28 in line with the 4 magnet Il o! the units order to positive line I8. v For relay 88.2; from negative line I8 (Fig. 1c) contacts R84. wire 28 (Fig. 1d), the 8 contacts I8 of the 9 key.- the 8 contacts RIOa, 8 wire 21 (Figs. lh `and 1m). the relay 8.8.2. wire 82 (Fig. ik), one of the 2 wires 28 of the units order (Figs. 1a, 1c. la), another of the contacts 28 in line with the 8 magnet I8 0f the units order to positive line I8. from negative line i8 (Fig. 1c). eeutects Rea. wire ze (mg. 1d), the seontacts la, the 8 wire 21 (Figs. 1h and-1m). relay (Fig. lk). one of the l wires 28 order (Figs. la, 1c. la). to oneof the :om 28 of the 1 magnet I8 in the units order, to positive line' I 8.- 1 For relay BIA: from negative line II8 (Fig. 1c), R-Ia, wire 28 (Fig. 1d), the 1 contacts I8 9. key in the tens order. the 1 contacts wire 21 (Fig. 1h), relay RIA, wire (Pig. 1g). one of the 4 wires 28 of the units `oi'der (Figs. 1c, 1a), pair oi' contacts 28 of the 4 relay I8 in the units order to positive line I8. Fhrrelay RIJ; from negative line I8 (Fig.v 1c) contacts Ria. wire 28 (Fig. 1d). the l contacts f 8 key in the tens order. the 1 contacts ima. the-1 wire 21 (m. 1n),.re1ay m1, wire u lg), one of the 2 wires 28 of the units order (Figs. lc. la), one of the contacts 28 4of the 2 'relay I8 oi' the units order. to positive line Il,

For relay RIJ; from negative line I8 (Fig. lc), `otliitaets R80. wire 28 (Fig. 1d), the 1 contacts I8 order. the 1 contacts Ella. the 1 wire 21 (Fig. 1h). relay RIJ, wire 88 (Fig. 1g). one of the 1 wires il of the units order (Figs.

wires 28 (Figs. 1h, ld, 1b); another of the contacts 28 of the 8 relay I8 in the tens order to positive line I8. I

The various product relays energized in accordance with Fig. 3 will have shifted their related contacts so that, if tens carries are disregarded for the moment, circuits will be completed through sets of indicating lamps 8| shown at the bottom of Figs. 1c, 1d, 1e and lf, to represent the units digits of the sum of the subproducts in the sev;- eral orders, that is, in the umts order the 5 lamp in the tens order the lamp circuits will be energized in accordance with tens carry requirements in a manner to be presently explained.

The circuit for illuminating the 5 lamp in the units order is traceable as follows and. is emphasized by heavy lines: from positive line` Il (Fig. llc), one of the contacts R8.8 a. one ofthe contacts Ella. one of the contacts RJAa (shifted), one of the contacts R414 (shifted), one o! the contacts R2.8a, one of the contacts Rua (lng. i9) shifted, contacts R2.2a, one oi' the contacts RIJa (shifted), one of'thecontacts R2.Ia, one of the contacts Rl.2a (shifted), one of the contacts RLIa (shifted), to the 5 wire of a group designated 82 (Fig. 1c), the 5 lamp 8| to' negative line I 8.

The circuit Just traced branchesin [Fig: Alo through a winding of the-magnet C8 to negative line I8, and Aalso branches at a higher point through a winding of relay magnet CI, so that concurrently with'illumination of the 5 lamp 4I in Fig. 1c, the relay magnets C8 and C8 (Fig. la) are energized. 'Ihese relays are termed carry relays, of which C8 will cause an additional entry of 2 in the tens order and the relay C8 will cause an additional entry of 1 in the tens order. These relays are shown in Fig. 1h in dotted outline where they shift relay contacts 08a and Cla respectively in the adding chain of the tens relay. Withthese carry relays energized along with the/subproduct relays already explained, the circuit to illuminate the 6 lamp 8| in the tens order (Fig. ld) may now be traced as emphasized in heavy lines from positive line I 8 (Fig. lm), contacts R8.8a, a second set of contacts R8.8a, one of the contacts R8.8a (shifted). one of the contacts Rtla (shifted), the left hand contacts 38.80 (shifted), the right hand contact Rtla (shifted). one of the contacts R2.8a, one of the contacts Ella (shifted), one or the contacts R4.2a, one oi the contacts R2.4a, one of the contacts R|.8a, one of the contacts Cla (Fig. 1h), one of the contacts 02a, one of the' contacts RLIa, one of the contacts Rua, one of the contacts R2.2a, one of the second set of contacts designated R2.2a, the lei't hand pair of contacts Rua (shifted), the right hand contacts RLla (shifted), contacts RLIa, the contacts Cla (shifted), contacts Cla, contacts R2.|a, contacts R|.2a, the second set of contacts R|.2a (shifted), contacts R2.|a, contacts Cia (shifted), contacts Cta, contacts Ri.|a (shifted), one of the second setfof contacts Rl.|a, the 6 wire of a group of wires designated 43 (Fig. 1d), the 6 lamp 4| in the tens order to negative line I6. From the circuit traced branches extend as emphasized in heavy lines to energize relay magnet C9 (Fig. 1m) and CH (Fig. 1h). Magnets C9 and CM are shown in dotted outline in Figs. 1n and 1i respectively, where the contacts controlled thereby are located in the hundreds order adding circuit chain.

'I'he circuit, for energizing the appropriate 2 lamp 4| in the hundreds order (Fig. le) is traceable through the emphasized circuit from positive line I5 (Fig. 1n), contacts R6.8a (shifted), contacts Cla, contacts R4.4a, contacts Cla, contacts Cta (shifted), contacts Rl.2a, contacts Ria (shifted), to the right hand contacts Rla, contacts C|0a (Fig. li), contacts CI la, contacts RLla, contacts R2.2a, contacts Rua, contacts C|2a, contacts Cl3a, contacts Clla (shifted), contacts R|.2a, contacts R2.|a, contacts Cita, Cla, Clla, contacts RLIa, the 2 wire M (Fig. 1e), the 2 lamp 4| in the hundreds order to negative line I6. Branching from this circuit are parallel circuits completed through relay magnets Cll, C20 (Fig. in), which are shown in dotted outline in Fig. 1i with their related contacts in the adding chain of the thousands order. The circuit through the thousands order is traceable from positive line l! (Fig. 1n) contacts Clla, wire 45 (Figs. li and 11), contacts Cisa (shifted), contacts C2011 (shifted), contacts C23a, C2la, C20a to the 8 wire of the group of wires designated 46 (Fig. 1f), the 8 lamp 4| in the thousands order to negative line Il.

All of the hereinabove traced circuits are completed substantially simultaneously, that is, since the multiplier and multiplicand keys are set to represent a pair of factors and with the multiplying key I1 (Fig.

are immediately completed and the lamps Il become illuminated to display the product 8265 of the example chosen.

Briefly reviewing the separate parts of the procedure the multiplicand keys eiect selective energization of the relays I0 (Figs. la and lb) which convert the digital values of the multipiicand into binary representations.- These relays then close related sets of contacts 23 which complete series circuit connections through the multiplier key 'contacts I2 to energize the subproduct relays in le) depressed, the circuit connections emphasized in heavy lines on the drawings lished at substantially the same time, with the entire system attaining what may be termed a condition of equilibrium or balance as represented by the emphasized circuits. As the system becomes adjusted, certain of the lishts 4| may flicker, but this is so rapid as to be barely perceptible to the eye and only the ultimately established circuits are prolonged to give a reading.

These circuits will remain completed until the factor keys are released by operation of the aero keys I0 and or until a new pair of factors is set up on the keyboard. Upon such new Bettina there will be a new selective setting of the relay magnets I6, a new selective setting of the subproduct relays and the carry relays, and ultimate completion of lamp circuits in accordance with the product of the new factors set upon the keyboard.

The principles underlying the adding chain arrangement may be better understood from the circuits extend between positive line Il (Fig. 1k) and negative line I6 (Fig. 1c). Wire |00 (Fig. ik) may be said to have a zero (0) value, and with all relays in the chain deenergized a series circuit extends upwardly to the 0 lamp 4| (Fig. lc). Between each group of like valued relay contacts, the connecting wires are separately identified as |0I between the Il and 32 groups of contacts. as |02 between the I2 and l groups of contacts. as |03 between the Il and I groups of contacts. as IM between the I and I groups of contacts, as lll between the 4 and 2 groups oi' contacts, and as |00 between the 2 and l groups of contacts.

The separate wires in each group are given values 0, 2, 4, 6 and 8 as indicated, and it will be particularly noted that, except in the case ofthe 0 wire, each continuous connection starting at any point and extending upwardly runs through wires whose values progressively double from section to section. To illustrate, the 2 wire |0| in section Il (Fig. 1k) has a value oi' 2 in that section. In section 32 its value is 4, in section I0 its value is 8, then going through the two sets of contacts it continues to the 6 wire |04 in section 4 (6 being the units digit of 16), then going through the three sets of contacts in section I it continues to the 2 wire |06 (2 being the units digit of 32), then through the two sets of contacts in section 2 it continues to the 4 wire |00 (4 being the units digit or 64'), and then through the contacts of section to the 4 wire 42 and 4 lamp 4|.

Thus, energization of relay RIJ in section 04 connects the wire |00 to the 2 wire |0I, and this wire value is repeatedly doubled (disregardins tens digits) tol ultimately arrive at a 4 lamp 4|. Taking as a further illustration the energization of a relay in section 32, the 0 wire |0| is connected over to the 2 wire |02, and tracing this wire the circuit passes progressively through the 4 wire |02, the 8 wire IN, the 6 (16) wire |05. the 2 (32) wire |00, and the 2 wire I2 to the 2 lamp Il. There is thus one less doubling of the initial 2 value for a 32 entry than for a 64 entry and similarly for a 16 entry the initial 2 value of wire |03 is doubled three times to a 6 (16) value. for an 8 entry the initial 2 value of wire Ill is doubled twice to an 8 value. for a 4 entry the initial 2 'value of wire |05 is doubled once to a 4 value.

It will be apparent that. where a relay is energized in each of two different sections, there will be a composite doubling, for example, where the contacts are shifted in both the 64 andl 0 divisor by each oi' and comparing each product obtained with the dividend to determine whether the product is to -V stead of through the multlplicand keys ii, as for Y"Qggr1g111, multiplying operations. The manner in l This dividend is set Plas. lc and 1d.

man, wire n "tnskeyboml pletesa -tbroush Tiisinltialilwire illconnectstothei thenthei illandwireill. In

the 8 wire iM (repreting 16+2), then to the 6 wire ill (represent- 2 wire |08 (representing an wire l! and2lampli. Thus, value voi section Il is doubled iive times uand combined with the 2 value of section l dou' bild twice. giving 64+!! or 72.

' Where more than one relay in a section is energiaed, there is an initial doubling or quadrupling as, for example, where in section 4, if all three relays were energized, the 0 wire i would Thus, the sum of three 4s is obtained by adding three 2s to get 8 and then doubling once toobtain 12.

In the uppermost section I, the contacts shift to raise the value of wires III by a single digit only, so that. all doubling is taken care of between wires ill and illand a l is added between wires ill and Il it required.

Division The multiplying mechanism Just described is utilised inthe performance of division which is carried out by automatically multiplying the a plurality of diilerent amounts greater, equal to or less than the dividend. The multiplying part of the operation linvolves automatic setting oi' therelays it in Figs. 1a and 1b sequentially represent diilerent amounts inch dividing is carried out may best be exby way' ofconcrete example.

`us assume accordingly a dividend of 8265. on the keys ii oi' Figs. 1c, 1d, leand 1f. and adivisor 95isset on the keys iii of This divisor` setting is exactly the same as the multiplier setting previously expi'ained. With the keys set to represent a divisor and a dividend. the division key lil (Fig. 1e) is depressed and latched by slide bar i2. The closure of related contacts li will thereupon complete a circuit from positive line il (Fig. le), con- (Fig. ld), which branches downwardly to energize relay magnet Ri whose return wire extends to negative line il. Thus, throughout dividing operations relay magnet Ri remains and holds its contacts Rib (Fig. 1d) contacts Ria (Fig. 1c) open to disconnect contacts i4 throughout the operation. These latter contacts, it will berecalled, caused energisation oi the relays il in accordance with the value of the multiplicand.

of the division contacts li also comfurther circuit traceable from positive line 'il (Flg..1e). contacts Il, wire I! (Fig. 1d), where line I2 branches upwardly to Fig. lb,

Ind

`al uns. 1e) te close contacts s1 which win initiate the dividing operations by completing a circuit from positive line il (Fig. le). contacts Ii, contaots Il, wire Il (Figs. 1d, lb). member il oi a u wire Il (Fig. 1a). thence through a wiper. Il, wire Il (Fig..1c)

- rest.

ring ot contact segments II, a cimtact wiper Il, nings contacts Sa of a relay designated S, a relay magnet SL, to negative line il. Magnet SL is of the slow acting type and upon closure of its contacts SLa will complete a circuit iromwire l2 (connected to positive line il as explained), through contacts BLa, magnet S to negative line il. The magnet S operates a stepping switch through a ratchet and pawl mechanism 6i (Fig. la). To the pivot shalt oi the ratchet are connected contact wipers I4 and l2 (Fig. la) and 0U and Il (Fig. 1b), which as the ratchet is stepped by repeated energization of magnet S will advance these wipers step by step to engage successive related stationary contactsegments or spots. As noted in Fig. 1a. the magnet S upon energization simply retracts the driving pawl and upon deenergization the pawl advances the ratchet under spring action as is well known in the construction of stepping switches.

Referring to Fig- 1b, When magnet S is energized, it also opens its contacts Sa which break the circuit to magnet SL and which in turn permits its contacts Sla to open to break the circuit to magnet S, whereupon the wipers are advanced one step. Advance of the wiper N (Fig. la) will break the circuit through the magnet R0 oi Fig. 1c. which was previously traced. and this circuit will not be again completed until the wiper Il has been advanced through 180 or ten steps. The wiper iii (Fig. 1b) functions as a control for the stepping switch to repeatedly energize magnet S and advance the several wipers ten steps of operation.

The initial energization oi' magnet SL, as explained, was brought about by manual operation of the key it and through wire 58. When the wiper 60 is on its 1 segment 59, it is disconnected to wire 58 and is connected to wire l2 (which is connected to positive line i5), so that a circuit is traced from wire l2, through `the l segment I9, wiper 60, contacts Sa, magnet SL to negative line it. Again, closure oi' contacts SLa energizes magnet S which in turn opens its contacts Sa, deenergizing magnet SL, the latter opening contacts SLa to -deenergize magnet S and enable the wipers to advance to the next step, where the operation is repeated. The .interval ot time between the steps is controlled by the slow acting magnet SL. This stepping thus automatically continues until wiper Bil is again at step iii, and since at this time there will no current in wire 58 the parts will come to When wiper 62 (Fig. 1a) contacts thei segment M, it completes a circuit from wire 52 (Fig. lb), contacts SLG, wire 88 (Fig. la), wiper 02, the l'spot I4, wire 81 (Fig. lb) relay Rii to negative line il. Relay Ril opens its contacts Riia to break any holding circuits therethrough at this time and, when wiper 82 advances, the relay becomes deenergized and contacts Riia again reclose.

When wiper I2 is on the 2 spot 8l, it completes a circuit from positive line il. to wire B6. as explained, wiper I2, the 2 spot 6l, wire 6l (Fig. lb), through the lower winding oi' the 8 magnet il in the tens order to negative line il. When the wiper 82 is on the 3 spot, a similar circuit is completed to energize the lower winding of the magnet.4 magnetv i8 in the tens order. When the wiper is on the 4 spot Il, a circuit is completed to energize the lower winding oi the 2 magnet il in the tens order. Thus. in turn the lower windoi the 1 magnet is of the tens order and on the lamps Upper then the lower windings of the 8. 4, 2 and l magnets I8 of the umts order are energized in succession, one for each step oi' the wiper 82, so that when the wiper 82 is in contact with the 9 spot 84, the circuit from wire 88 extends through brush 82, the 9 spot 84, wire 88, lower winding of the l magnet I8 in the units order to negative line I8,

Referring back now to the condition with wiper 82 on its 2 spot 84, which energizes theV lower winding of the 8 magnet I8 of the tens order, the energization of this magnet shifts its contacts 28, 24 and 28 and as a result multiplication takes place to obtain the product of the divisor X 80 4I, and this product '1600 is displayed on the lamps. Multiplying takes place in exactly the same manner under control of the divisor key contacts I8 and the contacts 28 of the 8 magnet I8 in the tens order as though this magnet had been energized under control of a multiplicand key, so that the multiplying circuits will not be traced in detail, and it will sufilce to point out briefly the relays that are energized' in the several orders for this multiplication of 80 and 95.

Thousands Hundreds RBS-M 111.8- i

the comparing mechanism operthe trial product 'Z600 with the At this point atea to compare divident 8265.

Referring to Figs. lc, ld, le and 1f, each of the keys I I when depressed will through a pin or roller 1I thereon rock a contact blade 12 toward the left to close a related pair of contacts 18 and all the other contacts 18 to the left thereof. Depression of a key II will also shift a pair4 of contacts 14 to open the upper and to close the lower contacts 14. In the units section of the machine (Fig. 1c) only the upper contacts 14 are required while in higher orders (Fiss. ld, le and 1f) both and lower contacts are provided. The function of the comparing mechanism is to deenergize the relay magnet I8 if the trial product is greater than the dividend. Where the trial product is less than the dividend, no effective circuits are completed.

Referring to Fig; 1I, the stationary blade of each contact 18 is wired to a coil of a relay R88 and through this coil to negative line I8. The movable blade of contact 18 is wired to upper contacts 14 whose common contact is connected through a wire 11 in parallel with the lamp 4I in the related digital position. The comparison of a multiplicand digitwith a trial product digit may best be explained by assumed conditions representing the three possible conditions of comparison. Let it be supposed that the 8 key II is depressed (closing contacts 1I in the 8 and 9 positions and closing lower contacts 14 in the 8 position) and the 8 lamp 4I is receiving current. This is an equa condition and, since the 8 wire 11 is in parallel with the 8 lamp 4I, this wire is connected back to positive line I8, through the lamp circuits From wire 11 there is then a circuit to the lower contacts 14 in the 8 position, relay'RlI to negative line I8. Assuming the trial digit to be smaller, i. e. the 8 key depressed and the '7 lamp lighted, no circuit is completed since ssamm the computed digit in an order are alike. relay R8I is energized, when the set digit is smaller magnet R88 is energized. and when the set digit is greater, neither R88 nor RII is energized.

In Fig. 1f a wire 18 is connected to the movable blade of contacts R88a and it will be apparent that. if the set digit in this order is smaller, wire 18 will be connected through left hand con tacts R880 to negative line I8. If the digits are equal, wire 18 connects through right hand contacts R881: and closed contacts R8Ia to wire 88 which in Fig. le corresponds to wire 18 in Fig. lf; I

If in this lower order the setI digit is smaller, contacts R8Ila will be in shifted position to connect wire 88 to negative line I8. The circuit to wire 18 runs similarly through the tens and units orders and it will be apparent that the relay R88 in the highest order, in which the set digit is smaller,

will prevail in connecting wire 18 to line I8 with the circuit for lower orders including the equal relay contacts R8Ia of higher orders In the units order no equal relay RBI is necessary, since this is the last position. The devices controlled through wire 18 will be explained as the present problem is traced.

Accordingly.' with 8265 set on keys II and 7800 set on lamps 4I, the set digits in the units, tens and thousands orders are greater than the trial digits and neither relay R8I nor R88 will be energized in these orders. In the hundreds order. the set digit 2 is smaller and the related relay RII will he energized. However, with the highest order prevailing, the contacts R in such order remain as shown (Fig. if) and wire 18 is not connected to line I8 and thus remains non-conductive.

Referring to Fig. lb, initial energization in the lower winding of the 8 magnet I8 of the tens order has shifted its contacts 28 to establish a holding circuit from wire 82 (connected to positive line I8), contacts RI Ia, upper contacts 8l of the 8 magnet I8, lower winding of the magnet, to negative line I8.

. Where as in the present example the trial product is smaller than the dividend, the 8 magnet Il will remain energized through this holding circuit when the switch 82 advances to the next step, where it energizes the 4 magnet I8 so that at that step both the 8 and the 4 magnets I8 are yenergized and multiplication again takes place. However, with the 8 magnet energized, the contacts 28 of the 4 magnet can not complete a hold- -ing circuit since the contacts 28 ofthis 4 magnet are connected to the now open lower contacts 28 of the 8 magnet, so that the 4 magnet cannot remain energized when the wiper advances to energize the 2 magnet I8. The contacts 28 of this magnet also cannot establish a holding circuit, so that again there is an idle multiplying operation which will be ineilective to hold the 2 magnet Il energized.

yBriefly stated, if the 8 magnet is held ener-l 

